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Alternate form of cos(n*pi)

  1. Oct 30, 2014 #1
    I saw somewhere that an alternate form of cos(n×π) was
    cos(n×π) = -1n+1
    But to me this does not make sense. Am I wrong?

    For n = 0
    cos(n×π) = 1
    -1n+1 = -1

    For n = 1
    cos(n×π) = -1
    -1n+1 = 1


    Is there another way to express cos(n×π) in an alternate form?

    PS. This is related to Fourier series.
  2. jcsd
  3. Oct 30, 2014 #2
    Nevermind, just realised what I did wrong.
    I did put -1^n instead of (-1)^n into my calculator.
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